[docker] Default server.name to hostname

The default server.name for docker images is currently "kibana".  When
running multiple instances of the docker image, this can cause confusion
when tracking metrics in the monitoring UI and status page.  Removing
this configuration will let us track using hostname.

Closes #44848

docs/setup/docker.asciidoc

@@ -120,7 +120,6 @@ The following settings have different default values when using the Docker
 images:
 
 [horizontal]
-`server.name`:: `kibana`
 `server.host`:: `"0.0.0.0"`
 `elasticsearch.hosts`:: `http://elasticsearch:9200`
 `monitoring.ui.container.elasticsearch.enabled`:: `true`

src/dev/build/tasks/os_packages/docker_generator/templates/kibana_yml.template.ts

@@ -17,7 +17,6 @@ function generator({ imageFlavor }: TemplateContext) {
   #
 
   # Default Kibana configuration for docker target
-  server.name: kibana
   server.host: "0.0.0.0"
   elasticsearch.hosts: [ "http://elasticsearch:9200" ]
   ${!imageFlavor ? 'monitoring.ui.container.elasticsearch.enabled: true' : ''}